47 lines
1.3 KiB
JavaScript
47 lines
1.3 KiB
JavaScript
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import postcss from 'postcss';
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const OVERRIDABLE_RULES = ['keyframes', 'counter-style'];
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const SCOPE_RULES = ['media', 'supports'];
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function isOverridable(name) {
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return OVERRIDABLE_RULES.indexOf(postcss.vendor.unprefixed(name)) !== -1;
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}
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function isScope(name) {
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return SCOPE_RULES.indexOf(postcss.vendor.unprefixed(name)) !== -1;
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}
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function getScope(node) {
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let current = node.parent;
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let chain = [node.name, node.params];
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do {
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if (current.type === 'atrule' && isScope(current.name)) {
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chain.unshift(current.name + ' ' + current.params);
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}
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current = current.parent;
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} while (current);
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return chain.join('|');
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}
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export default postcss.plugin('postcss-discard-overridden', () => {
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return css => {
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let cache = {};
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let rules = [];
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css.walkAtRules(rule => {
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if (rule.type === 'atrule' && isOverridable(rule.name)) {
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let scope = getScope(rule);
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cache[scope] = rule;
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rules.push({
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node: rule,
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scope
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});
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}
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});
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rules.forEach(rule => {
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if (cache[rule.scope] !== rule.node) {
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rule.node.remove();
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}
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});
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};
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});
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